With the graphics cards of the “Ada” generation, the new 12VHPWR connector is finding its way into the power supply. Since the power supply does not necessarily have to be built according to the new ATX 3.0 standard and does not have to have a 12VHPWR connection itself, there are also two backwards compatibility solutions for the 12VHPWR connector.
1. Possibility: Quadruple adapter included with the RTX 40
With the introduction of the PCIe power connector, two power levels were formerly defined by the PCI-SIG: 75 W for the 6-pin PCIe and 150 W for the 8-pin PCIe Plug. However, the PCI-SIG specification does not cover the fact that almost twice the current can flow through the connector, as specified by Molex for the Mini-Fit terminals.
This creates the dilemma for adapters that splitting the 12VHPWR connector into four 8-pin PCIe -connections must be made and that it must also be ensured that the called continuous power of maximum 600 W is ideally distributed over the four plugs in order not to exceed the limit of 150 W per plug.
2. Possibility: Adapted cable set from the power supply manufacturer
One option to avoid the cable flood is to use a cable set that can be connected directly to the connection panel of the power supply. Manufacturers such as Corsair, Sea Sonic and Thermaltake offer corresponding cable sets for existing power supplies, which implement a 12VHPWR connector from two 8-pin PCIe connectors. Unlike the existing cable sets, this ensures that the copper cross-section is increased to the 16 AWG recommended by Nvidia. Because the cross-section that has been common in power supplies up to now is only 18 AWG.
Continuous power of the 12VHPWR connector electrically coded
The power supply indicates how much power the graphics card can consume via a 12VHPWR connector via two of the four signal pins (Sense0 and Sense1) as described in the PCIe 5 standard or in the ATX 3.0 specification.
Adapters or adapted cable sets solve this determination of the continuous power by connecting the corresponding sense pins with Gnd pins without knowing how much power the power supply can actually provide. In the case of the adapted cable sets in particular, differently electrically coded cables would therefore have to be offered for power supply units of every performance class. However, the cable sets that will be available soon will all be activated for the full continuous output of 600 W. The “Corsair 12VHPWR 600W PSU cable” is titled as such and will be available in the manufacturer's web shop from September 29th. In a footnote to the press release, Corsair also adds that the corresponding power steps require a power supply rated from 750 to 1200W:
*600W load requires a 1200W rated CORSAIR PSU or higher. 450W load requires 1000W or higher. 300W load requires 750W or higher.
In this way, Corsair finally also gives a recommendation for the nominal power of its own power supplies according to ATX 2.x, with which it is ensured should be that peak loads can also be intercepted, as they can occur according to the new PCIe specification.
Terminals at the maximum of their current carrying capacity
However, in order for an adapted cable set with two 8-pin PCIe connectors to be permissible for a continuous output of 600 W at all, a single terminal must be able to carry a current of at least 8.3 A. The 7 A or 8 A (six live pins of the 8-pin PCIe connector), which Molex specifies as the maximum for a normal Mini Fit terminal, would be too tight, which is why special terminals like the Molex Mini Fit Plus HCS would have to be used.
3. Possibility: 12VHPWR natively from the power supply
Only if the power supply itself provides a 12VHPWR plug can it be assumed that the electrical coding of the plug has been selected in such a way that the load peaks can also be processed in addition to the permitted continuous power. For the 12VHPWR connector, in addition to the cable cross-section, the current carrying capacity for each terminal is specified at 9.2 A, such as the 12VHPWR connector from Amphenol should meet.
Tight bending radii or 40 mating cycles will melt connectors
Because the terminals of the 12VHPWR plug operate at the edge of their specification, increased contact resistance, if misused, can cause such heat build-up that the plug fuses. Such an observation is currently the reason for the PCI-SIG to monitor this fact more closely, as GamersNexus reports.
According to this, such a failure could be confirmed if the contact surfaces of the terminal are too small due to tight bending radii of less than 3 cm or if too many mating cycles damage individual terminals in such a way that their contact resistance increases excessively. The recommendation of many board partners is therefore, similar to that of Amphenol, not to carry out more than 30 mating cycles.
Summary of adapters, replacement cables and power supply innovations
The Nvidia presentation of the new generation of graphics cards has been accompanied by numerous announcements of power supplies that have the 12VHPWR connector. All corresponding power supplies known to date are listed in the picture gallery and table.
The second column of the table indicates whether a manufacturer offers replacement cables for existing modular power supplies or offers adapter cables.